Educated at Marlborough Grammar School and at Lewis Lochée's military academy in Chelsea, Whitelocke entered the army in 1778 and served in Jamaica and in San Domingo.

In 1807 he was appointed to command an expedition to seize Buenos Aires from the Spanish Empire, which was in disarray due to events in Europe.

[4] The attack failed and the British surrendered after suffering "the lamentable loss of a great proportion of the gallant army engaged in it.

This proceeding was regarded with great disfavour by many under his command and the British Army and public, and its author was brought before a court-martial[4] convened at The Royal Hospital in London in 1808.

[6] According to the judge-advocate presiding over the case, Whitelocke not only failed his objective of "the reduction of the province of Buenos Ayres," but also defeated the British hopes of "discovering new markets..., of giving a wider scope to the spirit and enterprise of our merchants, of opening new sources of treasure, and new fields for exertion in supplying either the rude wants of countries emerging from barbarism, or the artificial and increasing demands of luxury and refinement, in those remote quarters of the globe.